Domestic boilers are used to generate hot water, which may be used to flow through a circuit to provide heating to a facility, such as a home or office building. The hot water also may be stored in a hot water tank and used for hot water needs, such as running a dishwasher, shower and other domestic hot water uses.
Fuel-burning boilers commonly include a fuel-burning combustion device, or burner, to provide a source of heat to heat liquid water or steam. The burner may supply a hot gas mixture, which can be routed through a series of flue passageways. A boiler may further include two or more flue sections designed to transfer heat by way of convection from the hot gas mixture to liquid water or steam. The flue section typically can include one or more convective flue passageways through which the hot gas mixture can flow. In some boilers, the hot gas mixture can be routed through a sequence of flue passageways, each of which can be comprised of a series of flue passageway segments in a series of flue sections.
Additionally, the hot gas mixture can be routed in different directions through the flue passageway—for example, the hot gas mixture can be routed in one direction through a first flue passageway, and then in the opposite direction through a second flue passageway that runs parallel to the first, and so on, through a sequence of multiple flue passageways in the flue sections.
Generally, the flue sections of a boiler also include water passageways that are separated from the flue passageways by a solid wall, for example, produced from cast iron. The water passageway in the individual flue sections can be interconnected in order to permit liquid water or steam in the water passageways to flow between the flue sections, as well.
Furthermore, the flue passageways can include a series of convective fins attached to or formed from the solid wall and configured to extend into the flow stream of the hot gas mixture in order to transfer heat from the hot gases to the fins, and subsequently to the liquid water or steam on the opposite side of the wall in the water passageways.
Thus, hot gases from the burner can be routed to the first flue passageway segment of the boiler, where the hot gases pass over a set of convective fins around the perimeter of the flue passageway segment in order to transfer heat to the liquid water or steam in the water passageways. Thus, the flue passageway flow path is effectively divided into discrete sections by the convective fins.
In some boiler configurations, the combustion gases can travel along a combustion chamber wall and into one or more gas flow distribution channels, from which the combustion gases may the first flue passageway segment at a right angle to the flow direction of the flow distribution channel. In some boiler configurations, it has been shown that a disproportionately high portion of the hot gas mass flow travels to a far end of the gas flow distribution channel or channels, and into a last section of the flue passageway between an uppermost pair of convective fins and a far wall of the flue passageway.
Accordingly, it is desirable to provide a method and apparatus that more evenly distributes the hot gas flow through all of the flue passageway sections.